Abstract: To achieve the "dual carbon" goal, many carbon capture, utilization and storage (CCUS) technologies have developed rapidly in recent years, including oxygen-enriched combustion technology. However, conventional oxygen-enriched combustion technology relies on the flue gas recirculation system, which faces such problems as high construction costs, high operating energy consumption, and low-temperature corrosion of the recirculation pipelines. Therefore, eliminating the flue gas recirculation device and adopting only pure oxygen separated from air to achieve particle fluidization and fuel combustion is expected to reduce the total energy consumption and CO₂-capture costs. Basic structure of a self-designed 130 t/h pure oxygen combustion circulating fluidized bed (CFB) boiler was provided, and numerical simulation research on the gas-solid flow characteristics, combustion, and heat transfer characteristics of the CFB boiler based on computational particle fluid dynamics (CPFD) method was conducted. The calculation results show that there is a significant particle reflux phenomenon in the lower contraction section of the pure oxygen combustion CFB boiler, and the upper part of the furnace still presents a core-annular flow structure. In terms of combustion and pollutant emissions, the overall temperature distribution within the furnace is uniform, basically maintained at around 1 120 K. The oxygen concentration at the cyclone outlet is about 3.90%. The NO concentration gradually decreases with the increase of furnace height, and the original emission concentration of NO at the furnace outlet is about 100 mg/m³. From the perspective of heat transfer performance, the heat transfer coefficient of the heating surface in the furnace under pure oxygen combustion conditions has increased compared to traditional CFB boilers. The average heat transfer coefficients of the immersed tubes in the dense-phase zone and surrounding water wall are 394.8 W/(m²·K) and 179.9 W/(m²·K), respectively. The research results lay a foundation for further understanding the characteristics of pure oxygen combustion in CFB boilers and developing related boiler systems.